There are a bunch of "hard parts" involved, and even if you solve them, you don't replicate the experience of a social media site. The serving technology is ha

There are a bunch of "hard parts" involved, and even if you solve them, you don't replicate the experience of a social media site. The serving technology is hard. The dollar cost is high. The maintenance burden is high. The authoring experience sucks. The notification / distribution mechanisms are lacking. The feedback loops are broken. Social media sites are simple, free, zero-maintenance, trivial to post, notify/distribute to your friends and others, and build in a feedback system with both automated and human curation. There's an enormous amount of effort required to provide even a remotely similar level of service.